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Objective To improve the chemotherapy drug delivery to tumor by enhancing the tumor vascular perfusion induced by diagnostic ultrasound combined with microbubbles.Methods Ten healthy male sprague-dawley(SD)rats with total twenty walker-256 tumors implanted in the two back legs were randomized to the two paired groups: controlled group(C,n=10)and treatment group(T,n=10).Tumors in the controlled group were ultrasonic sham operated,while in the treatment group were treated by diagnostic ultrasound combined with microbubbles.The treatment group were taken contrast-enhanced ultrasound(CEUS)before and after treatment and analyzed the quantitative parameters.The microbubbles used in the treatment and CEUS was a kind of self-made lipid microbubbles called Zhifuxian.The 0.02 ml microbubbles were bolus injected at CEUS,while during treatment,0.04 ml microbubbles diluted into 1 ml saline solution were injected slowly at constant speed.Flushed by saline solution after treatment,the rats' tumors were harvested into three parts: one for chemotherapy drug concentration detected by high performance liquid chromatography(HPLC),one for HE detection,and one for Dox fluorescence intensity detected by confocal laser scanning microscopy(CLSM).The peak intensity(PI)values,the area under curve(AUC)values and the Dox concentration of each group were analyzed by pared-samples t test.Results(1)The contrast enhanced ultrasound quantitative analysis of the T group: PI value of the tumors before and after treatment were 66.22±16.25 and 75.74±17.67.The AUC values were 2937.52±677.51 and 3354.91±796.15.There was significant statistical difference between them(t=-5.212,-5.259,all P ＜ 0.05).(2)The Dox concentration of the T and C groups were(1.15±0.25)ug/g and(0.96±0.21)ug/g.There was significant statistical difference between them(t=2.403,P＜0.05).The Dox concentration of the treatment group was 1.2 times of the controlled group.(3)The pathology results of T and C groups: the tumor cells were arranged in cords,with big round deep-stained nucleus.No pathological changes were observed in the controlled group,and there was no significant difference between the two groups.But in the treatment group,tumor vascular congestion and inflammatory cell infiltration could be observed.(4)The confocal laser scanning microscopy(CLSM)detection of the T and C groups: the Dox red fluorescence was distributed in the tumor tissue interstitial,and the fluorescence intensity and distribution area of the treatment group were significant higher than the controlled group.Conclusions Diagnostic ultrasound combined with microbubbles treatment could significantly increase the blood perfusion in the walker-256 tumors of SD rats.Taking advantage of this vascular effect,the chemotherapy drug Dox could be delivered much more to the tumor tissue along with circulating bloodstream.With the addition of the sonoporation effect induced by the cavitation of the microbubbles,the chemotherapy drugs could be released much more to the tumor interstitial tissue.
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Objective To explore the effect of low intensity ultrasound (LUS) and microbubble enhanced ultrasound cavitation (MEUS), alone or in combination, on ethanol ablation (EA) of rabbit liver and observe the changes of liver perfusion and liver function. Methods Sixty-two healthy New Zealand rabbits were randomized to five groups: LUS group (n=6), EA group (n=14), LUS + EA group (n=14), MEUS + EA group (n=14), MEUS + LUS + EA group (n=14). For LUS, pulsed low intensity focused ultrasound emission was adopted (focal distance, 15 cm; duty cycle, 0.036%-0.22%;therapy duration, 5-6 min). According to the experiment design, surgically exposed left lobe of the liver was treated. In the LUS, MEUS + EA, and MEUS + LUS + EA groups, quantitative parameters were calculated and compared between the experimental and control liver lobes after different treatments. Three rabbits in each of the EA, LUS + EA, MEUS + EA, and MEUS + LUS + EA groups were used to detect the contents of alanine aminotransferase (ALT) and aspartate transaminase (AST) in arterial blood at five different time points (before treatment, 1 h, 48 h, 5 d, and 7 d after treatment). The livers of the remaining rabbits were harvested for measurement of ethanol ablation volume by drainage method or examination of the histological changes by HE staining 48 h after treatment. Results In the LUS group, the peak intensity (PI) and the area under the curve (AUC) were higher in the experiment lobe than in the control lobe, but there was no significant difference. In the MEUS + EA and MEUS+LUS+EA groups, the PI and AUC values were significantly lower in the experiment lobe than in the control lobe(PI:51.65±16.90 vs 101.09±14.41,44.08±8.46 vs 113.40±9.35;AUC:2183.06±501.13 vs 4258.54±841.21,1900.39±352.59 vs 4385.55±1198.16;t=9.059,16.835,9.630,7.932,P<0.001 for all). In the LUS group, no necrosis was observed, and the necrosis volume was 0 ml. The necrosis volumes caused by ethanol ablation in the EA, LUS+EA, MEUS+EA, and MEUS+LUS+EA groups were (0.84±0.27) ml, (2.42±1.11) ml, (3.52±1.34) ml, and (4.01±1.45) ml. The ethanol ablation volume was significantly lower in the EA group than in the other three groups (u=-13.800, -20.400, -23.400, P<0.05 for all),although there were no significant difference between any two of the latter three groups. No pathological changes were observed in the ultrasound exposed liver of the LUS group. In contrast, a wide range of coagulation necrosis area was noted in the other four groups. Compared with pre-treatment values, ALT and AST levels in all groups showed a slight rise after treatment, peaked at 48 h, and gradually returned to the pretreatment levels after seven days. The tendency of changes in ALT and AST levels with time was similar among the four groups (F=0.256, P=0.855; F=0.517, P=0.686). Conclusion LUS and MEUS, alone or in combination, could significantly increase the ethanol ablated volume of rabbit liver without aggravating liver function.